1. Field of the Invention
The present invention relates to a sine wave deflecting circuit for use in a cathode-ray tube of a television receiver.
2. Description of the Prior Art
It is known that, in a cathode-ray tube of a television receiver for example, sine wave deflection is performed in place of customary sawtooth wave deflection, as disclosed in, e.g., U.S. Pat. No. 4,672,449.
According to such sine wave deflection, there can be attained the following advantages.
(1) Any sharp variation of a deflection current can be suppressed due to the nonexistence of a retrace interval, so that a high-frequency disturbing component is decreased to consequently reduce a burden on a deflecting yoke.
(2) Since none of high voltage pulses is generated, a burden on the device is diminished.
(3) The deflection current frequency may be half a scanning frequency. Meanwhile, if the same current frequency is employed, a double scanning frequency can be obtained.
In the conventional sine wave deflecting circuit known heretofore, as described in the above U.S. Patent also, the means employed for generating a deflection current is based on the technique of first generating a sine wave signal of a low level and then amplifying the same. This technique, however, is disadvantageous in view of an extremely great power consumption.
There may be contrived a separately excited deflecting circuit where a resonant circuit is formed inclusive of a deflecting coil to keep oscillation while being driven by an energy supplied from an external oscillator. In such arrangement, however, a phase shift is prone to occur between the energy supply and the resonance to eventually bring about an extremely great possibility of causing operational instability.
Furthermore, in the case of using a resonant circuit, there arises another problem that exact external synchronization is not attainable with facility.